Association between heart rate variability and perioperative systemic inflammatory response

Objective: Colorectal surgery significantly affects homeostasis. The aim of the study was to identify patients with high inflammatory response to surgical injury, objectivized by the levels of C-reactive protein (CRP), interleukin-6 (IL-6) and white cell count (WCC) measured within 48 hours after the beginning of surgery by pre-operative measurement of heart rate variability (HRV). Design: Prospective, observational study. Setting: Department of Anesthesiology and Intensive Care Medicine, University Hospital Materials and methods: HRV was measured during orthostatic load one day before surgery. The patients were divided according to the HRV results into two groups: CAR (with cardiac autonomic reactivity, n=23), and NCAR (without cardiac autonomic reactivity, n=30). Serum levels of CRP, IL-6 and WCC were obtained at 0, 12 (only IL-6), 24 and 48 hours after the beginning of surgery. Results: The observed CAR and NCAR were significantly different at the levels of CRP at TO (6.5 +/- 5.1 mg/L vs. 16.4 +/- 23.2 mg/L, p<0.05), T24 (70.5 +/- 33.6 mg/L vs. 95.7 +/- 49.1 mg/L, p<0.05), T48 (103.1 +/- 42.4 mg/L vs. 159.0 +/- 63.4 mg/L, p<0.001), and IL-6 at T12 (79.3 +/- 42.2 pg/mL vs. 248.2 +/- 285.2 pg/mL, p<0.05), T24 (68.0 +/- 28.0 pg/mL vs. 239.6 +/- 245.8 pg/mL, p<0.001), and T48 (39.5 +/- 18.4 pg/mL vs. 195.5 +/- 162.9 pg/mL; p<0.0001). There was no significant difference in WCC between CAR and NCAR patients. Conclusion: HRV is a method for identifying patients with high perioperative pro-inflammatory response. Statistical differences in CRP and IL-6 levels between the studied groups increased over time. IL-6 was statistically significantly different already at T24, thus enabled earlier identification of patients with higher pro-inflammatory response when compared to CRP.